Dual fuel engine



June 5, 1951 p, s, 5|-||RLEY 2,555,818

DUAL FUEL ENGINE Filed July 24, 1946 2 Sheets-Sheet 1 IIEll i7 00 June5, 1951 P. s. SHIRLEY 2,555,818

DUAL FUEL ENGINE Filed July 24, 1946 2 Sheets-Sheet 2 g, 3Q Q 03 S M QRI 3 m H E m w 7 g m a an a N m N; R :3 m

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Patented June 5, 1951 UNITED STATES PATENT OFFICE DUAL FUEL ENGINE PaulS. Shirley, Hamilton, jOhio, assignjor, by inesne assignments, toBaldwin-Lima-Hamib ton Corporation, a. corporation of PennsylvaniaApplication July 24, 1946, Serial No. 685,872 sola'ims. (01. 123-198)This invention relates to an internal combustion engine of the type thatoperates with gas and oil fuels and is particularly directed to the fuelcontrols of such an engine.

In the operation of engines on a combined fuel cycle it is customary toinject a pilot quantity of easily ignitable fuel oil which, in turn,ignites the main charge of gaseous fuel. The gas is injected underpressure at or shortly after the commencement of the engine compressionstroke in such proportions that it will not ignite by the heat ofcompression alone. Thus the pilot injection of fuel oil is necessary forignition and proper combustion timing. Under normal full load conditionsthe quantity of oil is 5% to of the total fuel taken on a thermal basisso that nearly the entire load is carried as a result of the burning ofthe gas.

Gas injection valves may be positively operated or may be operated bypressure differential, but in either case it sometimes occurs that thevalve remains open beyond its intended period. If the valve is notclosed when ignition takes place in the associated cylinder, flamepasses back into the gas main and may create therein a seriousexplosion. Further, engines of this type operate ordinarily atsubstantially constant speed so that any radical departure from apredetermined normal speed is an indication of failure of one or more ofthe control elements so that the engine must be shut down before seriousdamage occurs.

The primary object of the present invention is to provide a controlsystem for a dual fuel engine in which the supply of gas is quickly andpositively cut off at the onset of any abnormal operating condition.

Another object of the invention is to provide a gas injection valve,functioning as part of a control system for a dual fuel engine in whichthe supply of gas is cut off whenever the injection valve fails tofunction normally.

Still another object of the invention is to provide a simple andefficient gas injection valve for a, dual fuel engine includinghydraulic means to open the valve during a predetermined part or theengine cycle and pressure operated means to cut off the supply of gas tothe valve should it fail to close at the end of its predetermined periodof opening.

Other objects and advantages of the invention will become apparent fromthe following specification, reference being had to the accompanyingdrawings in which:

Figure 1 is a diagrammatic view, partly in 2 section, of an engineembodying the present invention; Fig. 2 is a central vertical section ofa gas injection valve constructed in accordance with the invention; andFig. 3 is a sectional view of a suitable quick closing valve.

Referring to the drawings, and particularly to Fig. 1, an engine isshown comprising a cylinder It in which a piston ll operates to move across head [2, connecting rod I 3 and crankshaft M. The piston controlsexhaust ports l5 and scavenging air ports 15 in the usual manner. Itwill be apparent that the form of the engine is not important, that anysuitable va'lving for the exhaust and charging air ports may be used,that the engine may be single or double acting and that any number anddisposition of cylinders: may be used.

A pilot charge of fuel oil is injected into the cylinder at each strokeby a conventional injectionsystem including nozzle H and fuel pump I'8driven from the engine crank shaft in the usual manner. A main governor26, also driven by or in synchronism with the crank shaft and responsiveto .changes in the load thereon controls the fuel pump IB through a link2| and bell crank lever 22 the fulcrum of which is disposed to alter thequantity of fuel moved by the pump [8 at each stroke. The detailedconstruction of the pump is well known in the art and forms no part ofthe present invention. One arm of lever 22 is connected to the maingovernor and the other arm is made adjustable in length by any suitablemeans to provide any desired ratio of movement in a link 24 connectedthereto. The .adjustment may be illustrated as taking the form of ascrew connection .23 between link 24 and lever 22 whereby the end of thelink is movedtoward and away from the fulcrum of the lever 22 todecrease or increase the movement imparted to the link by a givenmovement .of the lever. Such a device thus serves to adjust the ratio ofmovement in the respectiveelements.

Link 24 is connected to operate a gas valve actuating pump 25 whichprovides hydraulic actuation of a gas injection valve 26 through pipe2.! in a manner hereinafter described. Actuating oil is supplied from areservoir 28 by a pump 29 and is passed through a filter 30 prior toentering the system. Return to the reservoir may be through bypass 3|,valved shunt line .32 or through .a return 33 from the -injection valve26.

Gas for the engine is supplied by a main containing gas under suitablepressure. A pres- .sure regulating valve 4! is interposed in thelineconnecting to the main, and a manual shut-off tothe engine cylinder.

valve 42 is also provided. In series with the manual shut-off 42 is aquick-closing or snap actuated valve 45 which may be of any suitableconstruction, one form being shown in Fig. 3. An air pump 43 isprovided, connected to the gas line by a valved passage 44, and is usedwhen the engine is operated on fuel oil alone as hereinafter described.

From the quick closing valve 45, gas passes directly to theinjectionvalve 25 through a line it, or to all injection valves in amulti-cylinder engine. The quick closing valve 45 is adapted to beoperated by any of three mechanisms each of which is responsive to adifferent abnormality. Thus the valve may be closed by an over-speedgovernor 56, by a low speed governor 52, or by sticking of the gasinjection valve 26. Either direct or relay connections may be usedbetween the operating instrumentality and the quick closing valve, adirect connection being shown in the case of the over-speed governor 50and a by draulic relay in the case of 'the low speed governor 52. Therelay may include a plunger 53 operating in a cylinder 54 to which oilunder pressure is introduced from conduit 55 whenever a valve 56 isopened. The valve 55 is controlled by the governor collar and oil may besup- 7 plied by pump 29 through a conduit 51.

whenever the pressure in the gas conduit exceeds the pressure in a frontchamber 64 between partition 6| and the cylinder end of the valve.

The main valve between the gas conduit and the engine cylinder isdesignated 65. This valve is journalled in the partition i andcooperates with a properly formed seat to close the passage closedposition by a spring 66 acting between partition 5i and a piston Blfixed to the rear of "the valve and working in a cylindrical bore 58 ofthe valve body. Piston 5'! acts principally to prevent the escape of gasrearwardly past the valve.

A hydraulic actuator for the valve 65 includes a piston ll] operating ina cylinder 1 I. The rear of the piston works in a cushioning cylinder 12to which actuating oil is introduced from conduit 2?. The piston isdrilled axially as at 14 and the passage so formedterminates inan'annular relief passage 15, communicating therewith by a small sidepassage. When piston H1 has moved forwardly a predetermined distance,annular relief passage is registers with a side return orifice l6permitting oil to pass through the piston to return conduit 33 by meansof passage 18. Further forward movement of valve 65 by piston is thusprevented whenever oil is permitted to flow into the relief passage. Theactuating system can be advantageously controlled at this point as wellas at the actuating pump by inserting a piston type discharge valve 80in passage '55 and loading the valve by a spring 82 acting on anenlarged valve head 84. The force of spring 82 is made adjustable bycontaining its outer end in a threaded cup 86. The force can thus bearranged so that discharge of actuating oil takes place only when thepressure in. passage 15 The valve 65 is urged to 4 reaches a definitevalue. The primary control of movement of the actuating piston II! is,however, derived from pump 25 which is preferably of the metering typecommonly used with Diesel engine fuel injection systems. The deliveryvalve of the pump, however, is removed for this service. Thecharacteristics and construction of these pumps are well known and canbe so chosen that the same precisely measured quantity of actuating oilis introduced at each stroke'at a given adjustment, and the adjustmentcan be readily changed to introduce a greater or less quantity into thesystem to cause. a greater or less duration of opening of the gasinjection valve 65.

An air bleeder screw is provided in the high point of the system and isinterposed in the return passage 18. A small hole 9| is drilled in thescrew 90 to form a continuous leak ofi passage from cushioning cylinder12. The cushioning cylinder, together with the shaped end of piston 79,from which lands 92 project, serves to prevent fiuctuations of thepiston and its associated valve '65 that might be caused by pressurewaves in the pressure line 21. Since the injector will ordinarily beassociated with others in a multicylinder engine, and long pressurelines are therefore necessary, such pressure waves are to be expected.

The rear end of injection valve 65 is provided with an enlarged stophead 93' to limit the movement of the valve toward the cylinder of theengine. Fouling of the valve by the engine piston is thus preventedshould the valve stick in open position. A leak off passage 94 is formedon the wall surrounding the chamber in which the rear end of the valvereciprocates, and lubrication pas"- sages 95 and 96 likewise enter theinjector body to maintain freedom of movement of the valve 65 therein atall points of support.

Considering now the front portion of the injector, as previously noted acheck valve 63 is provided to cut oif this space from the gas passage 46should valve 65 stick open. However, if a gas pressure of 20 pounds isused in the system,

the check valve will open for an undesirably long period in the cycle ifthe main valve becomes stuck so that more gas will enter the maincylinder than can safely be handled. In the event that the main valve 65sticks, th pressure rise in the main cylinder at and after thecompression stroke is so great that check valve 63 is held tightlyclosed, but this pressure exists only to a point in the cycle near theend of the expansion stroke so that gas could again flow into thecylinder at that time. The present invention effectively prevents thisaction by providing means to shut off the flow of gas whenever thepressure in cavity 64 rises to a predetermined level. This pressure iscommunicated through a conduit I00 to a cylinder I0! in which is dis- 7posed a piston I02 normally biased to one position by a spring or othersuitable device. Piston m2 is connected to quick closing valve 45 by a5. toggle mechanism having centers at I I5, I I6, and I I1. The lattertwo centers are at spaced points on a bell crank lever H8, an end ofwhich extends outwardly to connect to actuating rod I05. A spring I20,acting between lever I I3 and a cocking link l2l urges the lever H3downwardly, in a direction tending to close valve H0. So long as theline of centers H5, H6, H1 is such that center H6 is urged against linkI21, the valve will remain open, but as soon as the centers move out ofline in the direction away from the link the valve I I will snap shutand must be manually reopened.

Operation The engine, in operation, is started on fuel oil alone, maingas valve 42 being closed. If a ratio adjustment device such as isindicated is used, the gas valve actuating pump 25 is thus set for zerodelivery, but the gas is shut off at the manual control 42. Under thesecircumstances air supply pump 43 is put in operation by opening valve 44so that air is introduced through cavity 64 and past injection valve 65whenever the latter is open by periodic delivery from gas injectioncontrol pump 29. The temperature of valve 65 is thus kept within itsnormal operating range. At start, of course, the main governor 20 willbe in wide open position, but it is free to move the adjusting means ofthe fuel oil pump IS without affecting gas injection control pump 29.

When the engine reaches and stabilizes at its running speed, adjustmentof the gas-oil ratio may be made through adjustment 23 and link 24, andthe main gas valve 42 gradually opened. At the same time air supplyvalve 44 is closed. The engine thus attains its normal running conditionusing approximately to fuel oil and 90% to 95% gas, on a thermal basis,and fluctuations in the load are reflected in main governor so thatsimultaneous adjustment of pump and pump [8 are made. The arrangement ofthe fuel oil gas ratio can be made automatic depending upon the governormotion and the gas density and heating value of gas.

During normal running, gas valve 65 is opened periodically by adischarge of actuating oil from pump 25 and the temperature of the valveis maintained within its proper range by the flow of gas through cavity64 in the body of the valve. Check valve 63 remains open since, underproper running conditions, the pressure in the front chamber 64 of thegas injector will not exceed the pressure in the conduit 21.

Injection of gas continues so long as the discharge of pump 25 issufficient to maintain the main valve 65 open by pressure on actuatingpiston 10. As previously noted, the main valve 65 is limited in itforward movement by the projecting head 93. Since no discharge valve isnecessary to control properly the output of pump 25, oil is free to flowin both directions in the conduit connecting this pump with cylinder 'H.Fluctuations in the pressure in this line are smoothed out by cushioningcylinder 12 and by the spring loaded valve 80. As previously noted theduration of injection depends on the output characteristics and theadjusted position of pump 25 and actuating oil is returned to the systemthrough conduit 33.

So long as the engine operates normally, quick closing valve remainsopen. However, when an abnormality occurs in the form of a speedfluctuation exceeding a predeterminedvalue or when pressure in thechamber 64 of the gas injection valve 2'5 reaches a predetermined levelbecause of sticking or leakage of valve 65, bell crank lever I8 is moveddownwardly and the quick closing valve 45 is snapped shut. The operatormust then determine the cause of the failure and take steps to correctit before the engine can again be operated. In the event that thepressure in the front chamber 54 of the gas injection valve reaches apressure in excess of the pressure in the gas conduit, check valve .63will close so that the danger of flash-back to the gas manifold iseliminated.

While the invention has been described in conjunction with a particularform and disposition of the parts, it should be expressly understoodthat it is capable of numerous embodiments without departing from thescope of the appended claims.

Having thus described my invention, what I claim as new and desire tosecure by United States Letters Patent is:

1. In an internal combustion engine having a cylinder and operating atleast partially on gaseous fuel, a gas conduit, an injector having acavity connected to said conduit, a valve adapted to open communicationbetween said cavity and said engine cylinder, a check valve operating toclose the connection between said cavity and conduit whenever thepressure in the cavity exceeds the conduit pressure, and means to cutoff the supply of gas to the conduit whenever the cavity pressureattains a predetermined value.

2. In an internal combustion engine having a cylinder and operating atleast partially on gaseous fuel, a gas conduit, an injector having acavity connected to said conduit, a valve adapted to open communicationbetween said cavity and said engine cylinder, and means to cut off thesupply of gas to said conduit whenever the cavity pressure attains apredetermined value, said means being so constructed that the engine isshut down and the means must be reset before the engine can again bestarted.

3. In an internal combustion engine having a cylinder and operating atleast partially on gaseous fuel, a gas conduit, an injector having acavity connected to said conduit, a valveadapted to open communicationbetween said cavity and said engine cylinder, and means to cut oil thesupply of gas to said conduit whenever the cavity pressure attains apredetermined value, said last means including a quick-closing valvethat must be manually reset.

PAUL S. SHIRLEY.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,166,281 Ver Planck Dec. 28,1915 1,138,628 Cook May 11., 1915 1,280,201 Frazier Oct. 1, 19181,568,588 Cushman Apr. 11, 1925 1,846,654 Prechtel Feb. 23 19322,036,989 Buchi Apr. '1, 1936 2,294,152 Yates et a1 Aug. 25, 19422,423,728 Ray July 8, 1947

